Bombs fuses coupled axial impeller and generator rotor jointly shiftable rearwardly during launching to prevent rotation thereof

ABSTRACT

A bomb fuse having an impeller or turbine adapted to rotate upon release or launching of the bomb, the impeller being coupled to a detonator mechanism so that at the required instant, after a predetermined number of turns of the impeller, the motion of the latter is effective in moving the detonator mechanism into the armed position.

United States Patent 1 1 I 1 I 1 I 1 Inventor Jakhin Boaz Popper Kiryat Motzkin, Israel Appl. No. 802,112 Filed Feb. 25, 1969 Patented Oct. 12, 1971 Assignee The State of Israel, Ministry of Defence llaklrla, Tel Aviv, Israel Priority Feb. 27, 1968 Israel 29535 BOMBS FUSES COUPLED AXIAL IMPELLER AND GENERATOR ROTOR JOINTLY SHIFTABLE REARWARDLY DURING LAUNCIIING TO PREVENT ROTATION THEREOF 3 Claims, 2 Drawing Figs.

Int. Cl. F42c 9/02,

[50] Field of Search 102/86, 81.2, 70.2, 71

[56] References Cited UNITED STATES PATENTS 2,409,205 10/1946 Granumann 102/812 2,415,804 2/1947 Allison 102/86 2,644,398 7/1953 Rabinow 102/86 X Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Jerald J. Devitt Attorney-Kirsehstein, Kirsehstein & Ottinger ABSTRACT: A bomb fuse having an impeller or turbine adapted to rotate upon release or launching of the bomb, the impeller being coupled to a detonator mechanism so that at the required instant, after a predetermined number of turns of the impeller, the motion of the latter is effective in moving the detonator mechanism into the armed position.

PATENTEU no! 1 2:97:

I nuenlor JAKHIN BOAZ POPPER Q BOMIIS FUSES COUPLED AXIAL IMPELLER AND GENERATOR ROTOR JOINTLY SHIFIABLE REARWARDLY DURING LAUNCHING TO PREVENT ROTATION THEREOF This invention relates to bomb fuses and in particular to bomb fuses of the kind including an impeller or turbine which is adapted to rotate upon release or launching of the bomb as a result of the flow of air through the impeller blades, arming of the bomb being completed when the impeller has rotated by a predetermined number of turns and/or a predetermined minimum speed of rotation of impeller has been attained. Such a bomb fuse will hereinafter be referred to as a bomb fuse of the kind specified." As used in this specification the term "bomb" refers to any form of projectile containing a high explosive charge adapted to be launched or propelled by a mortar or other thrower or to be released by an aircraft.

:With bomb fuses of the kind specified, the impeller can be suitably coupled to the detonator mechanism so that, at the required instant, after a predetermined number of turns of the impeller, the motion of the latter is effective in moving the detonator mechanism into an armed position. Alternatively or additionally the impeller can be coupled to an electromagnetic generator the current output of which supplies an electronic signalling mechanism so that arming of the bomb can be effected when the turbine has attained the minimum speed required to generate sufficient current.

It is an object of the present invention to provide a new and improved bomb fuse of the kind specified.

According to the present invention there is provided a bomb fuse of the kind specified and comprising a fuse casing, aniinpeller located within the fuse casing, a rotor of an electromagnetic generator located within the fuse casing and coupled to the impeller, outer walls of the fuse casing in which are formed air inlet holes by means of which air can flow through thefuse casing so as to rotate the impeller, an internal body portion of said fuse casing, at least one ball bearing displaceably mounted with respect to said body portion, said impeller being supported by said ball bearing, spring-biasing means adapted to bear at one end on said body portion and at .the other end on said ball hearing so as to bias said impeller away from said body portion, the arrangement being such that said -impeller and said ball bearing are displaceable under the influence of launching accelerations and against the said spring biasing so as to bear directly on said body portion.

The disposing of the impeller within the fuse casing is distinctly advantageous as in this way the fuse retains its advantageous aerodynamic shape. By virtue of the particular mode of mounting of the impeller with respect to the casing it is ensured that during launching when the forces exerted on the bomb are very considerable the impeller and the ball bearing are directly supported by the body of the fuse casing whilst during normal flight the impeller is supported on the ball bearing and is free for rotation with respect to the bomb casing.

One embodiment of a bomb fuse of the kind specified will now be described by way of example and with reference to FIGS. 1 and 2-of the accompanying drawings which are longitudinal sections of the bomb fuse showing its disposition respectively before and during the launching.

As seen in the drawings the bomb fuse comprises a casing having a conical nose portion 1 and a substantially cylindrical body portion 2 a screw-threaded portion 3 being formed at an intennediate position on the body portion 2 so as to enable the fuse to be screwed into the body of the bomb (not shown). An impeller4 is mounted within the casing on an axle 5. The impeller 4 is rigidly and centrally coupled to the rotor 6 of an electromagnetic generator the coupling being such that a slight airgap 7 is maintained between the impeller 4 and the rotor 6 thereby allowing automatic dynamic balancing of the impeller 4 upon rotation. The impeller axle is formed with a shoulder 8 which bears on a first ball bearing 9 the outer component of which is fitted within a central bore 10 formed in the internal body portion 11 of the casing. An elongated extension 12 of the impeller axle 5 extends through a spacer sleeve l3 and then through a second ball bearing 14 also slidably mounted in the bore 10, this second ball bearing 14 resting on a nut 15 secured to the extension 12. The extension 12 of the impeller axle extends into the body of the fuse for purposes which will be referred to below. A compression spring 16 is located in the central bore surrounding the spacing sleeve 13 the upper end of the spring 16 bearing onthe upper ball bearing 9 whilst the lower end of the spring 16 bears against a retaining ring 17 set into the walls of the bore 10.

Inclined air inlet apertures 18 are fonned in the conical walls of the casing 1 above the impeller whilst air outlet apertures 19 are formed in the walls of the cylindrical portion 2 of the casing below the impeller 4.

As can be seen in FIG. 1 of the drawings, in the rest position of the bomb fuse, or in the position where the fuse is not subjected to accelerating forces, the compression spring 16 bearing via the ball bearing 9 on the axle 5 and in consequence on the impeller 4 maintains the impeller 4 spaced from the upper surface 20 of the body 11 of the casing thereby allowing for the free rotations of the impeller 4 when air flows through the inlet apertures 18. When, however, for example upon launching of the bomb fuse, the bomb is subjected to strong accelerating forces the impeller is pressed back causing the upper and lower bearings 9 and 14 to move downwardly and resulting in the impeller being firmly supported against the upper surface 20 of the internal body 11 of the casing. At the same time the compression spring 16 is strongly compressed and so as soon as the accelerating forces are removed or reduced the compression spring 16 presses the bearings into their original position wherein the impeller 5 is spaced from the body of the casing as before. It will thus be seen that during launching the considerable stresses acting on the impeller are not transmitted to the bearings but are taken up by the solid body portion of the casing whilst as soon as the bomb is launched and in flight the impeller moves away from the casing and is thereby given that rotational freedom required for arming of the fuse.

The impeller axle extension which projects into the body portion of the fuse can be coupled to a suitable detonating mechanism so that upon a predetermined rotation of the impeller disc the detonating mechanism is moved into an arming position. A suitable mode of coupling the impeller with the detonating mechanism is described in our copending Patent Application No.

I claim:

1. A bomb fuse comprising a fuse casing, said fuse casing including a leading end portion of substantially frustoconical form, an intermediate different portion of frustoconical form constituting a smooth continuation of the leading end portion, said intermediate portion being immediately behind said leading portion, and a trailing portion of substantially cylindrical form behind said intermediate portion, means defining a plurality of peripherally disposed air inlet holes in said intermediate portion, means defining a plurality of peripherally disposed air outlet holes in said trailing portion, means defining a passageway within said casing from said inlet holes to said outlet holes, an electromagnetic generator located within said casing, said generator including a stator fixedly mounted with respect to said casing and a rotor which is rotatable and axially displaceable with respect to said stator, an internal body portion of the fuse casing, at least one ball bearing, means mounting said ball bearing displaceably with respect to said internal body portion, an impeller, means coupling said impeller to said generator rotor, said impeller being supported by said ball bearing and being located within said casing in said passageway so as to be rotatable as a result of air flow between said air inlet holes and said air outlet holes, spring biasing means located within said casing, one end portion of said spring biasing means bearing on said body portion and an opposite end portion of said spring biasing means bearing directly on said ball bearing so as to bias the ball bearing, the impeller supported thereby, and the generator rotor away from said internal body portion, and toward said leading end portion, said impeller, said generator rotor, and said ball bearing being displaceable under the influence of launching accelerations and against the biasing effect of said spring biasing means, so that the impeller will bear on said body portion during launching and be shifted from said body portion during nonnal flight so as in its latter condition to be free for rotation.

2. A bomb fuse according to claim 1, which further includes means defining an axial bore within said body portion, an axle secured to said impeller and extending axially into said axial bore, a second ball bearing, said ball bearings being secure in 

1. A bomb fuse comprising a fuse casing, said fuse casing including a leading end portion of substantially frustoconical form, an intermediate different portion of frustoconical form constituting a smooth continuation of the leading end portion, said intermedIate portion being immediately behind said leading portion, and a trailing portion of substantially cylindrical form behind said intermediate portion, means defining a plurality of peripherally disposed air inlet holes in said intermediate portion, means defining a plurality of peripherally disposed air outlet holes in said trailing portion, means defining a passageway within said casing from said inlet holes to said outlet holes, an electromagnetic generator located within said casing, said generator including a stator fixedly mounted with respect to said casing and a rotor which is rotatable and axially displaceable with respect to said stator, an internal body portion of the fuse casing, at least one ball bearing, means mounting said ball bearing displaceably with respect to said internal body portion, an impeller, means coupling said impeller to said generator rotor, said impeller being supported by said ball bearing and being located within said casing in said passageway so as to be rotatable as a result of air flow between said air inlet holes and said air outlet holes, spring biasing means located within said casing, one end portion of said spring biasing means bearing on said body portion and an opposite end portion of said spring biasing means bearing directly on said ball bearing so as to bias the ball bearing, the impeller supported thereby, and the generator rotor away from said internal body portion, and toward said leading end portion, said impeller, said generator rotor, and said ball bearing being displaceable under the influence of launching accelerations and against the biasing effect of said spring biasing means, so that the impeller will bear on said body portion during launching and be shifted from said body portion during normal flight so as in its latter condition to be free for rotation.
 2. A bomb fuse according to claim 1, which further includes means defining an axial bore within said body portion, an axle secured to said impeller and extending axially into said axial bore, a second ball bearing, said ball bearings being secure in fixed spaced apart relationship to said axle, and both said ball bearings being slidable in said axial bore, said spring biasing means comprising a compression spring located in said bore and surrounding said axle, one end of said spring bearing against the ball bearing closest to the impeller, the other end of said spring bearing against said body portion.
 3. A bomb fuse according to claim 2, wherein the body portion against which the second end of the spring bears is located between said ball bearings. 